This invention relates to improved apparatus for the filleting of fish.
The traditional methods and facilities used for hand filleting of the more common species of fish such as codfish, have not varied significantly over the past many years. The usual procedure involves removing a fish from a fish box and placing it flat on a cutting table. Then, by using one or a series of knife cuts, depending on the size and type of fish as well as the technique preferred by the individual operator, a fillet is removed from the first side of the fish. The fillet is placed in a container and then the fish is rotated 180.degree., flipped over and a fillet is removed from the second side. The second fillet is placed in the container and the frame (head and backbone) of the fish is then discarded via a chute located to one end of the table.
The above-described procedure can be carried out fairly rapidly by an experienced operator, and in order to provide an incentive to the operator, most fish plants pay a bonus, which bonus is dependent on the operators' total productivity in terms of the weight of fish filleted per shift. Productivity however is not the only factor in an efficient processing operation. The "yield", which is a measure of the weight of fillets removed as compared with the overall weight of the fish, is also of great importance. A careless or unskilled operator may waste a great deal of edible flesh, i.e. more flesh than necessary may be left on the frame. For this reason fish plants traditionally pay close attention to the average yield as well as the total production of each operator.
It has been known for some time that the vast majority of operators obtain a higher yield on the first fillet removed from the frame as compared with the second fillet. Studies have shown that there are two main reasons for this. When filleting the second side of the fish, the first fillet has already been removed from the frame resulting in:
(a) relatively little clearance between the cutting surface and the cutting table making it difficult to pass the filleting knife parallel to the fish backbone;
(b) a gap between the cutting table surface and the fish frame in the area adjacent to the head. Therefore, the fish bows downwardly under the pressure of the cutting knife since there is no firm support underneath the fish frame.
Although the prior art has provided a number of devices for holding or supporting fish during a cleaning or filleting operation, none of them deal adequately with the basic problem created by the bowing downwardly of the fish and the curving of its spine after the first fillet has been removed and the fish has been turned over. U.S. Pat. No. 4,030,164 issued June 21, 1977 to Fick shows a filleting board having a curvate opening in its surface arranged so that the gill cover of the fish enters into it thereby to assist in retaining the fish in position. Most commercially utilized species of fish have gill covers streamlined with the head; hence guiding the gill cover into the opening would require a special time consuming effort which would result in productivity loss. From an operational point of view, the filleting of fish on Fick's device would require the operator to remove one fillet from the backside of the fish and the other fillet from the abdomen side, unless the operator would cut one fillet and then proceed to the opposite side of the board to remove the second fillet facing the backside of the fish. Needless to say, filleting from the back and abdomen side would result in poor yield and the necessary additional movement of the operator would take extra time and room. There is also no suggestion in the above patent of any means to support the cut side of the fish as well as the fish head so that the latter is retained as a straight extension of the spine of the fish during removal of the second fillet. The bowing problem referred to above is not dealt with by the Fick patent.
Studies have also been carried out by others on this problem especially by P. J. Amaria et al and reported in a paper entitled "Productivity Studies In Fish Processing"--Proposed New Method of Manual Filleting of Cod (presented at the Atlantic Fisheries Technological Conference, Williamsberg, Va. 1978). In that paper, a filleting board design is described, which design includes a large notch at one end of the board to receive the fish head during removal of the second fillet. The board surface was also sloped away from the operator at about an 8.degree. angle to make it easier for the operator to run the knife parallel to the cutting board surface. While the sloped board surface has been found to be advantageous, the particular notched board design described by Amaria et al has been found, as a result of subsequent tests, to have numerous disadvantages. There is an empty space below the notch and hence the fish head tended to droop downwardly into it in many cases thus causing the spine of the fish to arch upwardly. In other cases large fish heads would not properly enter into the notch. As a result the fish head was not supported in general alignment with the backbone. Furthermore the notch described by Amaria did not properly capture the gill or the cut portion of the head with the result being that the head tended to jump out of the notch when pressure was applied to the fish during fillet removal.